The real you, laid bareLook into the digital mirror to see your body as never before

Aviva Rutkin

SEVERAL months ago, at the Museum of Arts and Crafts in Paris, a couple wandered in front of a set of dark screens. Staring back at them was an image of themselves but with the skin stripped away, revealing organs, bones and muscle. Surprised, the woman gasped and covered her breasts, trying to shield herself from view.

She was looking into a digital mirror, a 3D installation that recreates what your body might look like on the inside.

Heres how it works: an individual undergoes a PET scan, X-ray and MRI scan to capture high-resolution images of their bones and organs. Altogether, it takes about three-and-a-half hours to collect this data. Then when you step in front of the mirror, a Microsoft Kinects

motion-capture camera tracks the movement of two dozen different joints, including the knees, elbows and wrists. That means the medical images can be animated with the help of graphical processing units so you can see your body inside out in real time. The mirror will go on show later this month at the Computer-Human Interaction conference in Toronto, Canada.

In an experiment, Xavier Matre, a medical imaging researcher at the University of Paris-South, and colleagues left 30 participants alone with the mirror for several minutes to gauge their reactions. In this instance, people were shown pre-recorded data of other individuals of the same sex. The team found that about one-third of people felt the same way as the woman at the museum uncomfortable in front of the mirror and

reluctant to let others see. When youre a child and

you discover your own image in front of the mirror, you dont know its you, says Matre. The initial reaction to the digital mirror is often similar. Its as if youre inside your body. Youre discovering something that belongs to you.

Matre and his collaborators built the digital mirror to explore philosophical questions about how we relate to our body. But in the future, they say they could imagine doctors using a similar system to help people explore a particular part of their body or prepare for an upcoming operation.

One-third of people felt uncomfortable in front of the mirror and reluctant to let others see

Warts and all

Other researchers have already started exploring how augmented reality can help medicine. Mirracle, another kind of mirror developed at the Technical University of Munich in Germany, projects slices of medical imagery directly onto a persons body. A different project recently featured at the American Association for the Advancement of Science conference in Chicago can animate MRI data on the computer screen, pinpointing parts of the body that might cause trouble in the future.

James Hahn, director of the Institute for Biomedical Engineering at George Washington University in Washington DC is investigating a similar technology for helping surgeons check background information while keeping their hands sterile. Using the Kinect, his lab has built a prototype interface that lets surgeons manipulate medical images with a few simple gestures.

Though Matres digital mirror is fairly experimental, Hahn says he can see how a future iteration could help educate patients in a new way.

Normally, the physician might show you an image of a CT or MRI of your body, but it is not in relation to your actual body. It might as well be someone elses CT, he says. If youre able to actually relate it to some parts of your body, it may give you a little more information about where the problem is.

Next up, Matre and his collaborators want to make the illusion even more lifelike by programming the heart to beat and the lungs to move. By visualising the body in more dynamic and medically accurate ways, we can learn more about how people see their own bodies, says Nadia Magnenat-Thalmann at the University of Geneva in Switzerland. There is a lot of work left to do to be able to have a proper perception of our inner self, she says.